Flameproofing composition



FLAMEPROOFING coMrosrrroN Linton A. Fluck, Basking Ridge, and Louis J. Moretti, Somerville, N. 3., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application December 23, 1952, Serial No. 327,695

11 Claims. (Cl. 252-8.1)

States Patent O decomposes to a considerable extent upon exposure to elevated temperatures and probably also upon aging, leaving acidic residues on the cloth which quickly destroy most of its tensile strength. In addition, there is usually an undesired yellowing of the textile material.

An object of the invention is to provide improved fire retardant compositions.

Another object of the invention is to provide an improved process for rendering flammable materials flame resistant.

A further object of the invention is to provide an improved flame resistant textile material.

Still another object of the invention is to provide a flame resistant fabric of softer hand.

Among other objects of the invention is providing an improved flame retardant composition of a sprayable type.

Various other objects and advantages of the present invention will become apparent to those skilled in the art from the accompanying detailed description.

This invention is concerned with a flame retardant composition, its application to textiles and the resulting treated textile material in which the composition contains a mixture of (1) a water-soluble salt of an oxygen-containing acid of pentavalent phosphorus, (2) a water-soluble polyalkylene polyamine, (3) a water-soluble nitrogenous compound selected from a certain group and (4) a certain softening and wetting agent.

The water-soluble salt of an oxygen-containing acid of pentavalent phosphorus provides phosphorus for flame resistance and desirably also contains at least some of,

the nitrogen required for a maximum flame proofing.

Diammonium hydrogen phosphate is the preferred phos phorus compound by reason of its low cost and relatively high efficiency but a wide variety of other phosphorus containing materials may be substituted if desired. These include, inter alia, guanidine phosphate, diguanidine pyrophosphate, sodium polyphosphate, ammonium metaphosphate, the mono-, di-, and trialkylamine pyrophosphates,

diguanidine polyphosphate, 'guanylurea phosphate, biguanide phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, ammonium polyphosphate, ethylene diamine phosphate, ethylene diamine polyphosphate, primary cyclohexylamine phosphate, primary morpholine. and secondary pyridine phosphates. Mixtures of such salts may be employed as well as salts of mixtures of such acids which include orthophosphoric acid, metaphosphoric acid and pyrophosphoric acid; the mixed acids being sometimes collectively called polyphosphoric acid.

The water-soluble polyalkylene polyamine serves to 2,784,159 Ce Patented Mar. 5, 1957 minimize yellowing of the textiles upon decomposition of the aforementioned phosphorous compound. This action is not understood as the amine has a striking effect in reducing the discoloration but a rather minor eifect in minimizing the losses of tensile strength from decomposition of phosphate salt. Hexamethylene tetramine is preferred but other substances may be used, including triethylene tetramine, tetraethylene pcntamine and other polyalkylene polyamines which preferably have a boiling point substantially above 200 C., as well as mixtures of such compounds. A comparatively small amount of this agent will perform the desired function, for example, from about 1 to about 15% of the polyamine based on the weight of the phosphate salt. The preferred quantity is between 1 and 10% on the same basis.

A water-soluble nitrogenous compound is the third ingredient, and this may be selected from the group consisting of cyanamide, lower alkylol cyanamides, dicyandiamide, ammonium dicyandiamide, lower alkylol dicyandiamides, ammonium cyanate, ammoniu thiocyanate, biuret, urea and mixtures of these substances. This material prevents an excessive loss of tensile strength in the textile fabric. Apparently, it is accomplished by the nitrogen-containing substance neutralizing any acidic decomposition products of the phosphate salt as fast as they are formed. In addition, it is thought that the nitrogenous compound furnishes some or all of the nitrogen which aids the phosphate salt in imparting flame resistance to textiles. In general from about 5 to about 100 parts by weight of the nitrogenous substance is used for each 100 parts of pentavalent phosphorus compound,

and the preferred amount ranges between 10 and 50 parts. Dicyandiamide is the preferred compound in this category. It has been determined that a nitrogenous compound from this group has comparatively little effect in minimizing the yellowing of a textile fabric for a sizable increase in the amount of this ingredient does not produce an appreciable reduction in discoloration of the fabric during heat aging tests.

A flame retarding agent satisfactory for many purposes can be manufactured by simply mixing the three ingredients described in detail above, as is apparent from Example A below. However, the product can be improved considerably particularly in regard to the hand or feel of resulting fabric and as to the solubility of the flame retarding mixture in water by the addition of one or more of certain softening and dispersing agents. In addition, the application of the treating composition to a flammable fabric is made much easier by reason of the increase in solubility as the temperature of a padding bath may be reduced from somewhat over 100 F. down to about F. Moreover, in the case of a mill which is not equipped with relatively expensive padding equipment, cloth may be thoroughly impregnated by spray application of a water solution of the flame-retarding composition because this softening and dispersion additive aids in thorough penetration of the fabric and permits the use of the relatively concentrated solutions that are especially desirable for spray application where the dripping of an excess of solution from the treated fabric during drying tends to cause streaking.

This fourth component of the flame-retarding composition is a wetting and softening agent of the type described in Patent 2,427,242 and more particularly in Example 4 thereof. it is made up of the condensation products of a 2 to i-carbon alkylene oxide with a mixture of an aliphatic amine salt of an N-aliphatic carbamic acid and an aliphatic-substituted guanidine salt of an N-aliphatic carbamic acid in which each of said aliphatic groups contains at least 12 carbon atoms. Preferably, from about 2 to about 10 moles of the alkylene oxide, ethylene oxide being preferred for the purpose, are condensed with each mol of said mixture of amine and guanidine salts. In general, it appears that the best results are obtained with between 5 and 7 mols of ethylene oxide per mol of a mixture of said salts in which the aliphatic radicals contain about 16 to 18 carbon atoms. The aliphatic constituents of such salts may contain longer carbon chains, as, for example, 22 or more carbon atoms, but it does not appear than any additional advantages are obtained with the higher aliphatic radicals.

In the detailed working examples below, an anionic surface-active agent containing a single long aliphatic radical of 12 or more carbon atoms was employed, namely, octadecyldisodium sulfosuccinamate. This anionic substance may be one of the higher alkyl sulfates, alkaryl sulfonates, or mono'esters or mono-amides of aliphatic sulfocarboxylic acids in amounts ranging from about 4 to about by weight of a mixture which also includes between about 80 and about 96% of the condensation products described above. ,However, the presence of this anionic component in the dispersing and softening ingredient is entirely optional, since its basic function of laundry fastness is a minor matter in the present flameretardant composition which is not of a wash-fast nature.

The desired improvement in the hand or feel of the treated textile fabric, as well as the effects of solubilizing flame-retardant compositions and increasing its penetration into the fabric, are obtained essentially by incorporation of the cationic condensation products of the aforesaid alkylene oxides and mixed amine and guanidine salts. The dispersing and softening effect of this additive is considered to be specific, as many wetting agents are known to be either incompatible or ineffective with the compositions of the present invention. For example, a number of well known classes of wetting agents are incompatible with the mixture of phosphate and nitrogenous substances disclosed herein, including the di-Z-ethylhexyl ester of sodium sulfosuccinate, tertiary-octyl phenol condensates with 10 mols of ethylene oxide and other alkylated aryl polyether alcohols. On a basis of dry weights, the flameretardant compositions should contain between about 0.2 and about 8.0% of the aforementioned alkylene oxidecondensation products of the amine and guanidine salts, and the preferred range extends between 0.4 and 5.0% on the same basis. Incorporation of more than 8% of this softening-dispersing material does not appear to enhance the product to an extent commensurate with the added cost. It is to be noted that the quantity of this agent is based on the dry weight of the total solids rather than the weigh of the phosphate salt alone.

The softening and dispersing agent employed in the examples below was prepared according to Example 7 of Patent 2,427,242 and has the following formulation:

PASTE SOFTENER Wt. percent Octadecylarnine and octadecylguanidine salts of octadecylcarbamic acid condensed with 6 mols of The aluminum sulfate and urea serve to stabilize the softening composition; and it is to be understood that these two ingredients are optional and may be omitted, if desired. As indicated previously, the sulfosuccinamate ester is also an optional ingredient. While the above paste softener is a convenient carrier for the essential condensate of ethylene oxide with the amine and guanidine salts, it should be noted that the active condensate constitutes only 32% of the total weight of paste softener and that the proportions set forth herein are expressed in terms of the active ingredient rather than the paste softener.

The flame-retardant compositions disclosed herein are suitable for the impregnation of any textile materials of a flammable nature including yarns, threads, as well as knitted or woven fabrics. It is contemplated that the field of greatest utility will be that of the natural and artificial cellulosic textile materials, including cotton, viscose rayon, ramie, jute, flax, linen, hemp, sisal, and the like, either alone or mixed with other natural or synthetic fibers of a non-cellulosic origin.

Many advantages accrue to the present invention. The flame-retardant agents disclosed herein are White to yellow powders with little or no tendency to cake in a container; hence they may be shipped and stored economically as concentrated materials rather than as relatively dilute solutions or emulsions. They can be padded onto fabrics at temperatures as low as F. because of their increased solubility. They may be applied at high bath temperatures, for example, 180 R, where desired, as, for example, in the case of very concentrated solutions of the order of about 25% solids. At such elevated bath temperatures, it is suggested that periodic additions of ammonia be made in order to maintain a substantially neutral bath. As indicated earlier, the product can be applied by spraying a solution onto the fabric. In this operation, a solution of the order of 20% concentration is recommended at a temperature of from about to about F. and a wet pickup of 80% is suggested. Too high a pickup should usually be avoided during spray application in order to prevent dripping of the solution from the fabric with probable streaking. Drying may be accomplished at room temperature or with heated equipment according to the desires of the finisher.

The treated fabrics of the present invention have been found to have a good resistance to loss of tensile strength and also to discoloration or yellowing upon heating. These qualities are, of course, of major importance in the case of curtains or drapes which hang near a hot radiator. There is little or no tendency of the treated materials to pick up moisture from the air, as is apparent from the examples below. Consequently, no migration of the fire retardant to the surface of the fabric occurs; there is no appreciable increase in weight of the material due to increase in moisture content and, therefore, no resulting sagging of the fabric; "and the impregnate-d fabrics remain clean longer as the dry fabrics do not tend to pick up dust to the same extent as a material treated with a hygroscopic finishing composition. The drier fabric also hangs better. Excellent fire resistance has been obtained along with little or no afterglowing or afterflaming in impregnated cellulosic fabrics. In compounding the fire-retardant formulation set forth herein, no chemical reactions were noted, hence it is believed that these compositions are purely physical mixtures. Further, no chemical reactions were noted between the fabric and the finishing agent during or after the impregnation. In comparison with fabrics treated by prior art non-durable fireretardants of the phosphate-nitrogen type, it was observed that the present treated fabrics showed less yellowing and less loss in tensile strength immediately after the treatment, and upon aging at elevated temperatures. The degree of impregnation of the fabric may be varied depending on the flammability of the particular fabric and the intended use. In general, it appears that a minimum of about 7% dry add-on is necessary to secure good flame 'form of application, inasmuch as the wet take-up of the agent can be more readily controlled by adjustment of the squeeze rolls.

Inasmuch as the impregnatedfabric described herein will not withstand washing without losing its fire resistant qualities, treated materials are preferably employed in uses wherein they need not be laundered frequently. For example, the impregnated textiles of this invention are especially suitable for draperies, theater curtains, welders aprons, painters dropcloths, etc.

The nature and objcctsof this invention arebest understood by reference to the following examples which are intended to be illustrative and, therefore, should not be construed in a limiting sense. Unless otherwise stated, all proportions are expressed in terms of weight.

Comparative Example A A sample of 80 x 80 unmercerized bleached cotton percale was tested for flame resistance by the method set forth below and found to burn completely. Afterglowing and smoking were also. observed. Other samples of the same cloth were subjected to grab tensile strength tests both before and after oven aging in the manner indicated below. Moisture regain tests were also made with the same fabric both before and after oven aging. vResults of these tests are listed in the table below for purposes of comparison.

Comparative Example B Diammonium phosphate, dicyandiamide and hexamethylene tetramine were blended to complete uniformity. An aqueous solution containing 15% solution of this mixture was prepared and applied to the same 80 x 80 cotton in a padder with the squeeze roll adjusted for an 80% wet pickup. After drying in air, the treated fabric was subjected to tensile strength, moisture regain and pH determinations both before and-after oven aging by the procedure set forth hercinbelow. The hand was also evaluated and the material checked for flame resistance. In addition a 20% solution was prepared and sprayed onto another sample of the fabric at 90 F. to determine if a spotted appearance resulted. The test data appears in the table below.

, Examples 1 to -9 Diammonium phosphate and hexamethylene tetrarnine were milled together with dicyandiamide for Zhours in a hammer mill. Then the solids were mixed in a blender made on certain representative samples before and after oven aging. However, the hand and flame resistance were evaluated in all cases. A 20% solution at 90 F. was sprayed onto the fabric in equipment adjusted to deposit suflicient solution to allow a dry take-up of 12%. These sprayed samples were studied only in respect to hand and appearance. In all instances the hand was found to be definitely an improvement over that of Comparative Example B and the impregnation was observed to be thorough and uniform without any crystallization spots. In addition, no yellowing or decrease in flame resistance was found upon heating each treated fabric at 300 F for 4.5 minutes.

Oven aging of the test fabrics was carried out according to U. S. Air Force Specification No. 16,155 with the cloth maintained at 158 F. for 24 hours, at 70 F. with a relative humidity for the next 24 hours, at 158 F. for the following 24 hours and at F. with a 65% relative humidity also for the final 24 hours.

Flame tests of the fabrics were made using a specially constructed apparatus and a procedure which followed in general that given in ASTM Tentative Specifications Designation: D626-41T, issued 1941, with minor variations in the size of sample and the tearing weight. Samples 2% inches by 10 inches were cut with the long dimension parallel to the warp and the other paralled to the fill. The apparatus consisted of a hood, a shield around the test piece, a Bunsen burner and a holder for the sample. The fabric to be tested was suspended vertically in the shield, which was placed in a hood with the fan off, the fabric being suspended in the shield by means of clamps at the top and bottom. The door of the hood was then closed. The burner previously regulated to a. luminous flame 1 /2 inches high was placed under the suspended sample so that the end of the sample extended inch into the flame. The flame was held under the sample for 12 seconds and then extinguished. The duration of after-flaming of the sample was measured by means of a stop watch. Any tendency of the sample to afterglow or smoke was noted and timed if possible. The total length of char in inches was measured by the tear length produced with a tearing weight of /2 pound. In none of these examples was any substantial afterglowing observed.

I Examples Dlammonlurn phosphate, parts Dicyandiamide, parts Hexamethylene totramine, parts-..

Paste softener, parts Active softener, percent of total solids.

Percent solids in solution.

Dry take-up on fabric, perce Hand Tensile strength (grab), lbs;

in war Percent moisture regain, oven agetL.

Flame retardant Average char length, inches Spray of 20% solution spots fabric.

100 100 100 '100 100 100 100 100 100 71 18.8 26.6 26.6 18.8 18.8 26.6 26.6 18.8 18.8 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 0 6.3 4.4 8.8 4.2 8.4 3.3 6.6 3.1 6.2 0 1.6 1.1 2.1 1.1 2.1 0.8 1.6 0.8 1.6 15 15 15.5 16 15.5 16 20.5 21 20.5 21 12 12 12 12 12 12 16 16 16 16 fair good good good good good good good good good 47 41 46 38 38 37 35 32 30 5.5 5.6 5.6 5.5 7.1 6.8 9.3 6.3 yes yes 3.1 2.3 no no solubility of the agent insuresthorough and uniform im- I pregnation and permits the application of an aqueous solution of the mixture to cloth by spray means.

While there are above disclosed only a limited number of embodiments of the composition, process and product of the invention herein presented, it is possible to produce still other embodiments without departing from the in ventive concept herein disclosed; and it is desired, therefore, that only such limitations be imposed on the appended claims as are stated therein or are required by the prior art.

Having described our invention, what we claim as new and desire to secure by Letters Patent, is:

1'. A flame-retardant composition of matter which comprises- 100 parts by weight of diammonium phosphate; between about 1 and about 15 parts of hexamethylene tetramine; between about 5 and about 100 parts of dicyandiamide; and between about 0.2 and about 8.0% by weight of said composition of the cationic condensation products of between about 2 and about 10 mols of a 2 to 4-carbon alkylene oxide per mol of a mixture of m aliphatic amine salt of an N-aliphatic carbamic acid and an aliphatic-substituted guanidine salt of an N-aliphatic carbamic acid in which each of said aliphatic groups contains at least 12 carbon atoms.

2. A flame-retardant composition of matter which comprises 100 parts by weight of diammonium phosphate; between 1 and 10 parts of hexamethylene tetramine, between 10 and 50 parts of dicyandiamide; and between 0.4 and 5.0% by weight of said composition of the cationic condensation products of between 3 and 7 mols of ethylene oxide per mol of a mixture of an aliphatic amine salt of an N-aliphatic carbamic acid and an aliphatiosubstituted guanidine salt of an N-aliphatic carbamic acid in which each of said aliphatic groups contains at least 12 carbon atoms.

3. A flame-retardant composition of matter which cornprises 100 parts by weight of diammonium phosphate; between 1 and 10 parts of hexamethylene tetramine; between 10 and 50 parts of dicyandiamide; and between 0.4 and 5.0% by weight of said composition of a mixture comprising between 4 and 20% by weight of octadecyl disodium sulfasuccinamate and between 80 and 96% of the condensation products of between S and 7 mols of ethylene oxide per mol of a mixture of the octadecylamine and octadecylguanidine salts of N-octadecyl carbamic acid.

4. A process which comprises impregnating a flammable nongelatinous cellulosic textile material with an aqueous solution of the composition of claim 1 and drying the material to produce a flame-retardant textile material.

5. A process which comprises impregnating a flammable nongelatinous cellulosic textile material with an aqueous-solution of the composition of claim 3 and drying the material to produce a flame-retardant textile material.

6. A process which comprises impregnating a flammable nongelatinous cellulosic textile material with a sufficient quantity of an aqueous solution of the composition of claim 2 to provide a dry take-up of at least 7% by weight of the textile material and drying the treated material to produce a flame-retardant textile material.

7. A process which comprises spraying an aqueous solution containing at least 10% by weight of the composition of claim 2 onto a flammable nongelatinous cellulosic textile material in sufficient quantity to provide a dry take-up of between 10 and 15% by weight of the material and drying the treated material to produce a flame-retardant textile material.

8. A flame-resisting textile material which comprises an initially flammable cellulosic textile material impregnated while in nongelatinous form with a flame-retarding quantity of the composition of claim 1.

9. A flame-resisting textile material which comprises an initially flammable. cellulosic textile material impregnated while in nongelatinous form with a quantity of the composition of claim 1 amounting to at least 7% of the weight of the material.

10. A flame-resisting textile material which comprises an. initially flammable cellulosic textile material impregnated while in nongelatinous form with a quantity of the composition of claim 2 amounting to between 10 and 15 of the weight of the material.

11. A flame-resisting textile material which comprises an initially flammable cellulosic textile material impregnated while in nongelatinous form with a quantity of the composition of claim 3 amounting to between 10 and 15% of the weight of the material.

References Cited in the file of this patent UNITED STATES PATENTS 2,106,938 Tramm et al Feb. 1, 1938 2,368,660 Hochstetter Feb. 6, 1945 2,427,242 Vitalis et al. Sept. 9, 1947 2,436,181 Rosser Feb. 17, 1948 2,452,054 Jones et al'. Oct. 26, 1948 2,452,055 Jones et a1. Oct. 26, 1948 2,606,115 Nuessle et a1. Aug. 5, 1952 2,632,743 Eckert Mar. 24, 1953 

1. A FLAME-RETARDANT COMPOSITION OF MATTER WHICH COMPRISES 100 PARTS BY WEIGHT OF DIAMMONIUM PHOSPHATE; BETWEEN ABOUT 1 AND ABOUT 15 PARTS OF HEXAMETHYLENE TETRAMINE; BETWEEN ABOUT 5 AND ABOUT 100 PARTS OF DICYANDIAMIDE; AND BETWEEN ABOUT 0.2 AND ABOUT 8.0% BY WEIGHT OF SAID COMPOSITION OF THE CATIONIC CONDENSATION PRODUCTS OF BETWEEN ABOUT 2 AND ABOUT 10 MOLS OF A 2 TO 4-CARBON ALKYLENE OXIDE PER MOL OF A MIXTURE OF AN ALIPHATIC AMINE SALT OF AN N-ALIPHATIC CARBAMIC ACID AND AN ALIPHATIC-SUBSTITUTED GUANIDINE SALT OF AN N-ALIPHATIC CARBAMIC ACID IN WHICH EACH OF SAID ALIPHATIC GROUPS CONTAINS AT LEAST 12 CARBON ATOMS. 